A new mouse laryngeal transplantation rejection grading system

Abstract

Objectives/Hypothesis: Development of a rat laryngeal transplantation model allowed for the first total human laryngeal transplantation by the senior author in 1998. In an effort to further our knowledge of the immune system's role in laryngeal rejection, a change to the mouse model was required. Prior to initiating immunosuppressive research protocols, a reliable mouse larynx rejection classification had to be established.Study Design: Animal study. Methods: Thirty-one mouse laryngeal transplants (C57 BL/6 donors to C3H recipients) were performed and allowed to reject. Six time points were evaluated histologically: 1, 3, 5, 7, 9, and 15 days post-transplant. Eight anatomic sites were evaluated and assigned a point value. A linear regression model was constructed using the group number as the response and the scores from the eight histological criteria as predictors. Severity classifications were determined by observing patterns in the sum of scores of variables found to be significant contributors. Group 1 was normal; group 2, minimal rejection; groups 3, 4, and 5, moderate rejection; and group 6, severe rejection.Results: All mice survived the transplants. Of the observed histological changes, cartilage, fat, muscle, and magnitude of lymphocytic infiltration significantly correlated with rejection severity. The rejection model created demonstrated 100% accuracy in predicting the severity classification for the 31 specimens in the study. Conclusions:The model established provides an accurate and reliable way to classify rejection severity in mice receiving laryngeal allografts. This sets the stage for future advanced study of manipulating the immune system as a mechanism for establishing allograft tolerance.

Long‐Term Laryngeal Allograft Survival Using Low‐Dose Everolimus

“…At days 30 and 60, the ARS remained in the minimal rejection range (2.46 and 2.78, respectively). All five allografts in the NI group were completely rejected at the 15‐day harvest time (ARS 6.01), which was consistent with our previous control rejection study 15. Compared with the NI group, everolimus‐treated mice had significantly less rejection at all time points.…”

“…The immune system was able to migrate to the organ but did not cause significant tissue destruction at any time point. In our previous rejection transplant study, larynges transplanted without immunosuppression had a profound lymphocytic infiltrate at 15 days, which was associated with complete allograft destruction 15. In the present study, fat nucleation was varied at 15 days but was almost uniformly absent thereafter, suggesting at least minimal rejection.…”

“…Rejection severity was graded on our laboratory's previously developed rejection grading scale 15. This scale has been proven very reliable, with 100 percent accuracy in predicting rejection severity.…”

“…A mouse laryngeal transplant rejection grading system was previously developed in our laboratory and has demonstrated 100 percent accuracy in predicting rejection severity 15. The grading system is based on chronological allograft rejection observed at the ultrastructural level with no immunosuppression given.…”

Tissue-Engineering Hollow Noncardiac Intrathoracic Organs: State-of-the-Art 2010

“…56 As re-epithelialization therefore appeared as an attractive strategy for airway grafts, Genden's group went on to show that subsequently the process could be significantly speeded up with the application of VEGF carried by a fibrin matrix to the mucosa. This view is tempered somewhat, however, by the observation that rat and mouse laryngeal grafts appear to exhibit early rejection throughout all tissues, not just the laryngeal mucosa, 63,153 and other 'compartments' within the larynx also contain antigenic tissue. Such strategies would also open the door to transplantation for the large pool of potential recipients with laryngeal cancer.…”